There are conventionally known navigation devices and navigation systems for searching a route from a desired departure point to a destination and providing guidance to a user using map data and road data, and examples of such navigation devices and navigation systems that have been implemented include car navigation devices that are mounted in an automobile and that provide route guidance to a driver, and communication-type navigation systems that send route search requests to a route search server and receive the results to receive route guidance using a mobile telephone as a terminal device for navigation.
In particular, a communication-type navigation system is a system that uses a mobile telephone or other mobile terminal as a navigation terminal, and is also used as a navigation system for pedestrians. There are also navigation systems for pedestrians that preferably have a route guidance function that includes modes of transportation and have, in addition to searching and providing guidance for walking routes, a function for collecting operation timetable data and routes for modes of transportation in a route search server, and for searching and providing guidance for routes (boarding-candidate train) from a desired departure station to a desired destination station in addition to searching and providing guidance of walking route. There are also transportation guide systems for receiving and displaying routes for modes of transportation, timetables, boardable trains, and other distributed information from an information distribution server that does not provide route searches for walking routes.
Route search devices and route search methods used in general navigation devices and communication navigation systems are disclosed in, e.g., Patent Document 1 (Japanese Laid-open Patent Application No. 2001-165681). This navigation system is configured so as to send departure point and destination information from a mobile navigation terminal to an information distribution server, search from road network and transportation network data in the information distribution server, and provide guidance for a route that matches the search conditions. Used as one search condition for a route search is movement means from a departure point to a destination, examples of which include walking, automobile, railroad, and other modes of transportation in combination with walking.
The information distribution server uses the positions of connecting points and curve points of roads (routes) in a map data as connection points as nodes, and the route that connects the nodes as links, and is provided with cost information (distance, time required) of all the links as a database. The information distribution server references the database, and is capable of sequentially searching for links that reach from the node of the departure point to the node of the destination, following nodes and links that minimize the cost information of links, and providing guidance to the mobile navigation terminal about the shortest route. A method referred to as the label determination method or the Dijkstra method is used as the route search technique. A route search method that uses the Dijkstra method is disclosed in Patent Document 1 noted below.
Route search systems for searching routes using transportation systems are provided with an operation timetable database in which operation timetable data of transportation systems have been organized into a database on the basis of departure time, departure point, destination, arrival time, and other route search conditions specified by the user; and are provided with data in which the transportation network has been organized into a database on the basis of the above. The route search systems are configured to reference these databases, connect a departure point and a destination that includes transit changes (transfers), sequentially follow usable modes of transportation (individual trains and shuttle buses) as a route, and present one or a plurality of candidates for route guidance (departure station, destination station, course, train, and other modes of transportation) that matches the route search conditions. Route search conditions that can be specified commonly further include required time, number of transit changes, fares, and other conditions.
A user operates a mobile terminal, inputs a category of store or event and desired region to be searched, and requests the search to be provided with information about stores and events. The server searches for a store or event that corresponds to the specified category and that is present in the region, and the information is transmitted to the map display terminal. In the provision of the timetable, the timetable of the route is presented on the screen of the display device of the mobile terminal when the user operates the mobile terminal and specifies a route. In the transfer guidance, the user specifies a departure point and a destination point, whereby a recommended route is presented.
It is also possible to connect a PC, a mobile telephone, or another terminal device to a map server on the Internet; to input a desired spot, facility and store address, name, telephone number, or the like to download map data in a predetermined range that includes the spot and the position of the facility and store; and to display a map image on the display device.
The map data for displaying a map image in a communicative-type navigation system is commonly composed of vector map data rather than bitmap data (raster map data) for reducing the amount of data during communication. The vector map data is composed of polygon data for displaying roads included in a map in mesh units in a state approximate to natural geographical features, and road data in which road links are expressed as vectors. The road data expressed as vectors are used when a guidance route or a route history are drawn on the map image. The present position of the map display device is drawn on the route or road data that is searched in route guidance. The present position is calculated by a satellite navigation method using a GPS receiver disposed in the map display device.
Map data and route search network data provided to a common routing guide system is data related to a region (referred to herein as service area) to which the system provides routing guide service. For example, an ordinary routing guide system is designed for domestic service in a certain country, or is designed for service in a specific region in a certain country.
In such a case, there is no problem in a route search or route guidance as long as the departure point and destination are within the service area of a certain routing guide system. However, the total route cannot be searched or guidance provided from a departure point to a destination in the case that the departure point is within a certain country and the destination is located in another country. The reason for this is that the route that the routing guide system on the departure point side can search and provide guidance for has a range that lies within the country of the departure point side, and is not provided with map data and route search network data of the other country of the destination side.
In an onboard navigation device or the like, map data and route search network data of a specific region are stored in the onboard navigation device; and when a spot outside of the area is set as the destination, the route search depends on a server provided with map data and route search network data of the entire country that includes the other region. Alternatively, a method may used in which a route search is enabled on the navigation device side by downloading the map data and route search network data of the lacking regions.
For example, such a routing guide device has been disclosed in Patent Document 2 noted below (Japanese Laid-open Patent Application 2003-97960). The routing guide device uses starting points midway in the route as a plurality of candidates when route search from the departure point to the destination is carried out in a central facility. When the starting points are transmitted to the routing guide device, the routing guide device determines and transmits to the central facility the starting points for which guidance can be provided. The central facility carries out a route search from the departure point to the starting points, and the guide device is designed to carry out a route search from the starting points to the destination and provide an optimal route from the departure point to the destination.
A map display system is disclosed in Patent Document 3 (Japanese Laid-open Patent Application No. 2001-4392) noted below in which the present position or destination point information is transmitted as a map search condition from a mobile telephone as a terminal device to a map server, guidance information and map information are generated by a map server and distributed to the mobile telephone in accordance with search conditions, and the guidance information and map information are combined in the mobile telephone and displayed on the display device.    [Patent Reference 1]: Japanese Laid-open Patent Application No. 2001-165681 (FIGS. 1 and 2)    [Patent Reference 2]: Japanese Laid-open Patent Application No. 2003-97960 (FIGS. 1 and 2)    [Patent Reference 3]: Japanese Laid-open Patent Application No. 2001-4392 (FIGS. 4 and 6)